Merriam-Webster defines the word "yo" as an interjection used to grab someone's attention. A new app called "Yo" is certainly taking that definition to a new level in the past few days.

The app, which is available in the Apple and Google Play stores, allows users to connect and communicate using the word "yo," and that's it. It's perhaps one of the most simple app concepts ever created, and though it may sound too simple to succeed, developers have raised over $1 million from investors. Think Progress reported that the app's inventor just quit his job in Israel and moved to San Francisco to focus on the future of the app. So far, about 50,000 users have sent about 4 million "Yo's."

The app's description in the Apple Store explains it best:

Wanna say "good morning?" Just yo.

Wanna say "Baby I'm thinking about you?" - Yo.

"I've finished my meeting, come by my office" - Yo.

"Are you up?" - Yo.

After users download the app, they are prompted to create a username and allow the app to access contacts. When contacts download the app, the exchanges of "yo" can begin. As the app's description says, "the possibilities are endless."

The app is blowing up on social media and bringing out the sarcastic humor in everyone, but the best gems are in the App Store's product reviews.

One user writes, "Not just a means of simple but effective communication, Yo is a way of life. Since downloading Yo, all my relationships have improved and I've regrown most of my hair."